This is a phase I trial of an investigational drug called GNKG168 in patients with relapsed and refractory acute lymphoblastic leukemia (ALL) and acute myelogenous leukemia (AML) who are in morphologic remission but are positive for Minimum Residual Disease (MRD). GNKG168 is a Toll-like receptor (TLR) agonist. TLR agonists are a novel approach to stimulate an effective anti-tumor immune response as they are able to stimulate both innate and adaptive immune responses. There will be two strata i.e patients who have received hematopoietic stem cell transplant (HSCT) and patients who have never undergone HSCT. GNKG168 will be administered as a 60 min iv infusion. One 14-day cycle consists of 5-day treatment followed by 9 day-rest. Patients will receive 2 cycles before evaluation. The primary objective is to determine the maximum tolerated dose of GNKG168 in relapsed ALL and AML patients.